Ubuntu Booting Variations and Troubleshooting

I used a variety of computers for testing the USB boot process. Every computer acted differently to different boot configurations.

• Every computerwith Boot from USB support was able to boot the original boot.img file. They were all able to install over the network.

• Most computers were able to boot the Ubuntu Live Desktop operating system when my 1-GB thumb drive was formatted as a USB floppy drive. However, one computer gave a generic boot error message.

• Only my newer computer systems could boot the USB hard drive with the ext2 file system. It didn’t make any difference if I used a real USB hard drive or thumb drive. In addition, specifying the ZIP configuration was the only way to make the hard drive configuration work on one of the computers.

• My Asus netbook had no issues booting from any of these configurations, and it even worked from a 2-GB SD Card.

Depending on the configuration variation and hardware that you use, you may see some well-known errors.

• Blank screen—If all you see is a blank screen with a blinking cursor, then something definitely did not work. This happens when the boot loader fails. It could be the result of failing to install the boot loader properly, or it could be a BIOS problem. Try rebuilding the USB drive in case you missed a step. Also, try booting the USB drive on a different computer. If it works on one computer and not on another, then it is a BIOS problem. But if it fails everywhere, then it is probably the boot loader.

• ‘‘PCI: Cannot allocate resource region. . .’’—This indicates a BIOS problem. You may be able to boot using additional kernel parameters to bypass the PCI errors, for example:

live noapic nolapic pci=noacpi acpi=off

However, you may not be able to get past this. Check if there is a BIOS upgrade available for your computer.

• Root not found—There are a variety of errors to indicate that the root partition was not available during boot. This usually happens when the USB drive is still initializing or transferring data, and not ready for the root partition to be mounted. You can fix this by extracting the initrd file and editing the conf/initramfs.conf file. Add in a mounting delay of 15 seconds (the new line should say: WAIT=15). This delay gives the USB time to initialize, configure, and transfer data.

Source of Information : Wiley Ubuntu Powerful Hacks And Customizations